Mt. Cuba Center's Sam Hoadley Will Present 'Knockout Natives' on April 13 in Bridgehampton

The next guest in the Horticultural Alliance of the Hamptons’ monthly lecture series will tout both the horticultural value and ecological importance of native plants, and offer his plant recommendations, when he delivers his talk, “Knockout Natives,” on the afternoon of Sunday, April 13, in Bridgehampton.

Sam Hoadley is the manager of horticultural research at Mt. Cuba Center, a nonprofit botanical garden in Delaware dedicated to the conservation of native plants and their habitats. His role involves managing plant trials, collecting data, writing research reports and coordinating volunteer endeavors to collect pollinator data — “which is a huge effort that is only made possible thanks to those volunteers,” he said during an interview last month.

Consisting of citizen scientists, the Pollinator Watch Team observes insects in the trial gardens to identify the plants that beneficial insects are most attracted to and determine what value various native plants and cultivars have. It’s one of many ways that Mt. Cuba Center assesses and rates plants.

Hoadley’s intention is to present the best of both worlds: very high-performing plants in terms of both their beauty and their prowess in supporting wildlife.

A Primer on Mt. Cuba Center

Mt. Cuba Center was formerly the estate garden of the du Pont Copelands, who moved there in the early 1930s from Litchfield, Connecticut. Hoadley said they selected the site because it looked similar to the landscape they had come from in Western Connecticut.

“The space they chose was a hilltop that, at the time, was a fallow cornfield, and they got to work building the home and eventually the gardens,” he said. “And pretty quickly, they recognized their passion lay in gardening with wildflowers, and the preservation of open space also became very important to the Copelands.”

Hoadley described the family as ahead of their time in thinking about native plants and conservation. Even in the mid-1900s, they recognized that a lot of open space in northern Delaware was being eaten up by development, and they recognized the need for open space preservation and wildflower conservation, he said. “They wanted their home garden eventually to be a place where people could come see these wildflowers.”

After Pamela Cunningham Copeland died in 2001, the estate garden began to transition to a public botanical garden, and now Mt. Cuba Center welcomes 30,000 visitors a year and offers educational opportunities.

While it may be a relatively new public garden, Mt. Cuba Center has incredible established landscapes from decades of cultivation with forward-thinking design, Hoadley said.

Bridging the Gap

Hoadley acts as the liaison between Mt. Cuba Center and commercial nurseries, sharing data ahead of the public release and even sharing plant material. The goal is to ensure that plants are available for consumers to buy and add to their home gardens when Mt. Cuba Center publishes its plant recommendations.

“We really want to avoid situations where we promote plants that you just can’t buy,” he said.

Being unable to find appropriate plants on the market is a challenge for native plant enthusiasts.

“For an average home gardener, some of these things are just not as accessible as I think they should be,” Hoadley said.

Mt. Cuba Center also offers native seed collection workshops that include how to scout for plants, how to collect an appropriate amount of seed so as to not put pressure on a plant population and how to propagate those seeds.

“It is a little bit of a learning curve, but it’s all very possible,” Hoadley said.

He noted that Mt. Cuba Center’s trials have evolved over the years. Previous trials were very “cultivar heavy,” studying what is commercially available and presenting a market evaluation of what could be purchased at nurseries. More recently, the trials have incorporated more species plants, i.e., plants that have not been substantially altered through selective breeding. Hoadley explained that these are plants that, for whatever reason, have been overlooked by the nursery industry.

“We found that some of these locally native species that are just not in the nursery trade are actually great garden plants,” he said. “But they also have wider applications, not just home gardens, but also in restoration projects and for land managers.”

Hydrangeas 
Come in Native Options

Hydrangeas, which are almost synonymous with Hamptons gardens, are an example of a highly desirable flowering plant that comes in both native and nonnative varieties. Hoadley said some native hydrangeas are every bit as garden worthy as the ubiquitous, beloved nonnative species.

For example, the popular Endless Summer hydrangeas are cultivars of the species Hydrangea macrophylla, which is from Asia. But Hydrangea arborescens, commonly called smooth hydrangea, is a wild hydrangea that is native to New York and the eastern United States.

The issue with nonnative hydrangeas, Hoadley said, is that their flower buds for the following year are formed in the late summer and fall, and those flower buds must survive the winter on the plants. If there is a brutally cold winter or a really cold spring, “your floral displays out of those plants could just be nonexistent for the next year,” he said.

He explained that nonnative plants do not respond to the same environmental cues that native plants do. The nonnatives may begin their growth too early, and if there is a hard freeze or a big temperature swing after bud growth has started, “those flower buds can be zapped.” Once that happens, that’s it, he said. “You won’t get more flowers out of those plants.”

During his talk in Bridgehampton, Hoadley will review results of Mt. Cuba Center’s trial of Hydrangea arborescens, aka smooth hydrangeas, which he said are incredibly reliable plants that can be cut to the ground in the spring. “They still will bloom for you. They’re just tough as nails, and they produce a very reliable display every year.”

Natives Vs. Cultivars

To accentuate desirable traits such as bigger blooms and longer blooming seasons, plant breeders have developed cultivars of native Hydrangea arborescens, such as Annabelle and Incrediball. They aren’t truly native plants because of that human intervention, but they are closer to home than cultivars of nonnative species.

Hoadley said “cultivar” is unfortunately a very broad term that captures many types of plants. “I tend to think about cultivars as a spectrum of almost human manipulation or human influence,” he said.

This can range from human selection of a wild plant that exists in nature and is chosen for gardens because it is different, beautiful or disease resistant, to heavily manipulated plants that have been bred, selected and hybridized for many generations, he said, adding, “and sometimes those plants don’t very closely resemble their wild counterparts.”

Those differences may not be as concerning as some would make them out to be.

“I would say the biggest critique of cultivars from some of the native plant community is that cultivars don’t provide as much ecological value as wild-type plants — species plants from wild populations,” Hoadley said. “And that is true, and it’s not true all at the same time. We find that selections often retain a lot of their ecological value.”

Heavily manipulated plants, especially when the flower types have been modified in a fundamental way, have less ecological value, he said. “But it’s very rarely zero wildlife value.”

The value of plants exists on a spectrum, he said, and there is a lot of gray.

He said Mt. Cuba Center’s philosophy is “conservation by addition,” and he encouraged adding even just one native plant to a garden to join the native plant movement.

The biggest thing that Mt. Cuba Center does is empower people to be part of the greater solution by providing more value to wildlife, Hoadley said.

Sam Hoadley will present Knockout Natives at the Bridgehampton Community House, 2357 Montauk Highway at School Street, Bridgehampton, on Sunday, April 13, at 2 p.m. Admission is $10, or free for members of the Horticultural Alliance of the Hamptons. Visit hahgarden.org for more information.